1. Field of the Invention
The invention relates to a differential pulse code modulation arrangement having an input for receiving a sequence of samples to be encoded, an output for supplying encoded samples, processing circuits, more specifically:
a differential circuit for producing differential samples between the samples to be encoded and prediction samples, PA1 a prediction circuit to produce prediction samples from encoded samples.
2. Prior Art
An encoding arrangement of this type is used with particular advantage in digital television.
In this type of usage, the problem is the speed of the processing operations to be effected. Actually, if one wants to encode a television picture at a picture element rate of 13.5 MHz, an interval of 74 ns is available for a processing operation.
When locking into conventional differential pulse modulation arrangements, it appears that this 75 ns interval, once it has been distributed over the operation to be effected by the differential circuit, by the prediction circuit and also by other circuits - such as the quantizing circuits etc. . . . - is not long enough for the available circuits.
For that reason it has been proposed to effect different operations in parallel by the processors: see the article "DISTRIBUTED VLSI PROCESSORS FOR PICTURE CODING", by S. C. Knauer, published in ICC 84 Conf. Rec. (Amsterdam, Netherlands, May 84), pages 718-723.
The arrangement described in said article has the following disadvantage: it requires the same number of processors as there are parallel operations to be effected, not counting the interconnection circuits to be provided between the processors.